Generally, a vehicle nowadays has many electronic control units (ECU)s installed in the vehicle, and among those ECUs, some have a self-diagnosis function for diagnosing an abnormality of the vehicle, which may be designated as On-Board Diagnostics (OBD). In recent years, OBD II standard is enacted, which is applicable to most of gasoline-engine vehicles and diesel-engine vehicles. According to the OBD II standard, the abnormality of the vehicle and the vehicle parts are diagnosable based on a regular monitoring of critical components and other conditions, such as an engine, an exhaust gas and the like.
The ECU stores information indicative of abnormality of a vehicle to a memory unit when diagnosis items are diagnosed as abnormal, based on information of various sensors that are installed in a vehicle, which is then read out by an external device installed in a gas station or the like. The read-out information is utilized for an abnormality check or the like. See for example, a patent document, Japanese Patent Laid-Open No. 2004-151021 (patent document 1).
When the self-diagnosis function is not properly functioning, the abnormality of sensors is not appropriately diagnosable. Therefore, the function of the abnormal sensor is configured to also be diagnosable as is (i.e., as the sensor is installed in the vehicle), and the diagnosis results are stored in the memory unit.
For example, according to the OBD II standard, the abnormality diagnosis determination items and the abnormality diagnosis inspection items (i.e., designated as abnormality diagnosis items) are stored as readiness information in the memory unit when satisfied. In other words, when all items of the readiness information are satisfied, the vehicle is shippable from a factory, or is returnable to a user from a repair shop.
The readiness information is erasable (i.e., can be “cleared”) by the external device according to the OBD II standard, which means the information is erasable from the memory unit. Here, the readiness information is considered as complete only after all abnormality diagnosis items are satisfied. The ease of satisfying an abnormality diagnosis item is different from item to item, and the time required for the determination of the diagnosis item also varies from item to item. In other words, a certain diagnosis item may take a very long time to be determined as satisfied when such an item is cleared. Therefore, especially when the vehicle has to be diagnosed in a short time in a shipping process from a factory or in a repair process before returning to a user from a vehicle dealer, such a long diagnosis time, for completing/satisfying all abnormality diagnosis items, is problematic.